Abstract: A dielectric rotary coupler for electromagnetic waves of the microwave frequency region structured of a substantially ring-shaped rotary member and a stationary member, each member being formed of a dielectric waveguide, or line, having a rectangular cross-section. The rotary line and the stationary line are arranged to face each other with a predetermined space therebetween along a coupling length, through which a microwave, for example, a carrier microwave FM-modulated by a signal reproduced by a rotary head of a VTR, is coupled from the rotary line to the stationary line, or vice versa.